We have been able to miniaturize coagulation procedures, so that it is possible to measure fibrinogen, the prothrombin time, partial thromboplastin time and Factors V and VIII in as little as 1/2 ml. of plasma. Having established values in a small group of "well" premature infants, we intend to continue to study those in whom sepsis, Rh incompatibility or hyaline membrane disease associated with DIC is suspected. Heparin responsiveness is variable. Preliminary studies indicate that heparin resistance may be related to the level of fibrinogen. Response will be measured by a barrage of clotting assays in patients receiving 100/u. kilo of the drug. Preliminary studies have shown that approximately 1/3 of children with sickle cell disease show definite abnormality in platelet aggregation when measured with ADP, Epinephrine and/or collagen. We intend to study platelet function in depth in these children, both when they are free of, and during episodes of crises. A new technique has been evolved showing that platelets similar to white cells are able to migrate in tissue culture chambers. The inhibiting effect of plasma from patients with ITP will be analyzed. The platelets of certain subjects with asthma are non-responsive to epinephrine. We intend to determine if the defect resides in the platelets or the plasma of such subjects.